This invention relates to telephone systems and in particular, to bridges used for interconnecting a plurality of subscribers' lines for direct current (DC) security alarm purposes and the like.
A bridge typically comprises a plurality of terminal pairs for connection to subscribers' lines and circuitry for interconnections of the lines. The bridges are or four-wire two-wire or four-wire and may provide for handling various numbers of subscribers' lines, typically three-line or three-way to twentyfour-line or twentyfour-way.
A single DC alarm circuit typically consists of one continuous loop from the alarm company over a two-wire telephone circuit to the central office (C.O.) where the circuit is distributed to the subscribers and finally back to the alarm company once again through the C.O. The distribution of the alarm circuit is accomplished with a DC alarm bridge which simply loops the circuit in and out of the C.O. to the subscribers. The alarm company's service is impaired when any of the two-wire telephone circuits fails (i.e. becomes open, shorted, etc.). To return the DC Alarm Bridge to working order for the remaining "good" subscriber circuits, the faulty circuit must be removed and a 0 ohm resistor (or short) put in its place. This is referred to as "termination" of the circuit.
When problems arise in service utilizing bridges, the telephone maintenance personnel must locate, identify and repair or replace the component or components or the line or lines causing the problem. Trouble shooting is accomplished by systematically disconnecting a subscriber's line from a bridge and substituting a terminating line for the subscriber's line. If the trouble is no longer present after this substitution has been made, the maintenance person knows that the problem is in the subscriber's line. Then the line can be tested and repaired. If the trouble is still present after a substitution, the substitution is reversed, that is, the terminating line is removed and the subscriber's line is reconnected, and the process is repeated for another subscriber's line. This is difficult and time consuming approach which requires a maintenance person to work at the bridge or at terminals leading to the bridge, which usually are found in crowded conditions of difficult access.
It is an object of the present invention to provide a new and improved apparatus for use in testing bridges, especially DC Alarm Bridges. A particular object is to provide such apparatus which permits disconnecting and reconnecting of subscribers' lines and connecting and disconnecting of terminating lines by service personnel at a location remote from the bridge, and without requiring any physical movement of communication lines and/or terminating lines. An additional object is to provide for such remote operation over existing equipment, such as a dual tone multi-frequency telephone hand set (DTMF) and a POTS lines.
It is an object of the invention to provide apparatus for testing bridges which provides for disconnecting and reconnecting of individual lines very quickly and with a maximum of effort, thereby decreasing service requirement time and line down time. An additional object is to provide such apparatus which can be utilized with various types of series connected communication lines, including various sizes of bridges.
Other objects, advantages, features and results will more fully appear in the course of the following description, wherein the drawings merely show and the description merely describes the preferred embodiments of the present invention which are given by way of illustration or example.